1. Field of The Invention
The present invention relates to a locking mechanism for a cam lever used in a pin grid array socket, especially a locking mechanism for retaining the cam lever in a tightened status and preventing the latter from leaving the status due to tension existed in the contacts of the pin grid array socket.
2. The Prior Art
Conventional pin grid array sockets normally comprise a cover defining a plurality of upper passageways therein and slidably engaging with a base which defines a corresponding number of lower passageways retaining contact therein. The upper passageways and the lower passageways are in constant communication with each other. A cam is received in a space defined between the cover and the base and operative to move the cover along the base thereby positioning the socket at either a loosened status ready for insertion of pins of the CPU or a tightened status forcing the pins of the CPU to abut against the corresponding contacts. When the socket is in the loosened status, the pins of the CPU are inserted into the upper passageways and the lower passageways with a substantially zero insertion force (ZIF), but are not in electrical contact with the contacts retained in the lower passageways. The cam is then operated to drive the cover to move laterally along the base thereby urging the pins of the CPU module to electrically connect with the contact of the base. The CPU module is moved by the cover of the socket when the socket is changed from the loosened status to the tightened status.
The CPU module is commonly engaged with a heat sink for heat dissipation. However, due to the high density of modularization, the CPU module is heavy and has a large dimension. Thus, the addition of the heat sink causes the assembly of the CPU module and the heat sink to be larger and heavier which in turn causes difficulty for the cam to drive the cover on which the CPU module and the heat sink are seated.
To solve the problem, U.S. Pat. No. 6,017,234, which is enclosed herein for reference and which are invented by the same inventors of the present application, discloses a two-layer ZIF PGA socket comprising a mother housing having a first recess and a hole defined in an edge of the first recess, a beam exposing to the hole and the first recess and a pivot extending from the beam. Two daughter housings are slidably received in the first recess of the mother housing and each daughter housing comprises a C-shaped head portion extending out the mother housing and defining a second recess for loosely receiving the beam of the mother housing. The C-shaped head portions of the daughter housings are matingly configured to define a first reception space therebetween and together are movable along a same direction. A cam lever comprises a cam and a handle bar connected to the cam. The cam is rotatably received in the first reception space between the daughter housings and defines a hole for rotatably receiving the pivot of the mother housing. A first block and a second block extend from the cam and both are spaced away by the hole of the cam and the beam of the mother housing for respectively driving the configured daughter housings to move in opposite directions when the handle bar is manually operated in different directions.
Although U.S. Pat. No. 6,017,234 can solve the problems encountered in the prior art, it has a minor problem to be solved, that is the retention of the cam lever in the tightened status may not strong enough to retain its status because the tension of the contacts may force the daughter housings to move backward and leave its tightened status.
It is requisite to provide a locking mechanism configured with the cam lever for retaining the cam lever in the tightened status and preventing the latter from leaving this status due to tension existed in the contacts of the pin grid array socket.